Transmission Of Can Controller - Fujitsu MB90420/5 (A) Series Hardware Manual

MB90420/5 (A) SERIES F

23.7 Transmission of CAN Controller

When 1 is written to TREQx of the transmission request register (TREQR), transmission by the message
buffer (x) starts. At this time, TREQx becomes 1 and TCx of the transmission complete register (TCR)
becomes 0.
n Starting transmission of the CAN controller
If RFWTx of the remote frame receiving wait register (RFWTR) is 0, transmission starts immediately. If
RFWTx is 1, transmission starts after waiting until a remote frame is received (RRTRx of the remote request
receive register (RRTRR) becomes 1).
If a transmission is requested to more than one message buffer (more than one TREQx is 1), transmission is
performed from the lowest-numbered message buffer.
Message transmission to the CAN bus (by the transmit output pin TX) starts when the bus is idle.
If TRTRx of the transmission RTR register (TRTRR) is 0, a data frame is transmitted. If TRTRx is 1, a
remote frame is transmitted.
If the message buffer competes with other CAN controllers on the CAN bus for transmission and arbitration
fails, or if an error occurs during transmission, the message buffer waits until the bus is idle and repeats
retransmission until it is successful.
n Canceling a transmission request from the CAN controller
• Canceling by transmission cancel register (TCANR)
A transmission request for message buffer (x) having not executed transmission during transmission wait
state can be canceled by writing 1 to TCANx of the transmission cancel register (TCANR). At completion
of cancellation, TREQx becomes 0.
• Canceling by storing receive message
The message buffer (x) having not executed transmission despite transmission request also performs
reception.
If the message buffer (x) has not executed transmission despite a request for transmission of a data frame
(TRTRx = 0 or TREQx = 1), the transmission request is canceled after storing received data frames
passing through the acceptance filter (TREQx = 0).
Note: A transmission request is not canceled by storing remote frames (TREQx = 1 remains unchanged).
If the message buffer (x) has not executed transmission despite a request for transmission of a remote
frame (TRTRx = 1 or TREQx = 1), the transmission request is canceled after storing received remote
frames passing through the acceptance filter (TREQx = 0).
Note: The transmission request is canceled by storing either data frames or remote frames.
n Completing transmission of the CAN controller
When transmission is successful, RRTRx becomes 0, TREQx becomes 0, and TCx of the transmission
complete register (TCR) becomes 1.
If the transmission complete interrupt is enabled (TIEx of the transmission complete interrupt enable register
(TIER) is 1), an interrupt occurs.
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MC-16LX FAMILY 16-BIT MICROCONTROLLERS HARDWARE MANUAL
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